E 



134 



VOLCANIC ROCKS OF 



Upper 

 Gallery, 



Wall-case 1 



burning lake, which was, as nearly as we could judge, 300 

 or 400 feet lower. It was evident that the large crater had 

 been recently filled with liquid lava up to this black ledo-e." 



The lavas of Hawaii appear to have been in a very 

 fluid state, as will be seen on reference to specimen No 

 20, &c. 



They have also been poured out in enormous quanti- 

 ties ; a stream of basaltic lava, two miles broad and 25 

 miles long, proceeded from an opening in Mauna Loa 

 13,000 feet above the level of the sea. (Lyell's "Princi- 

 ples," p. 383.) 



In June 1840 a stream of melted lava continued to flow 

 for three weeks into the sea, in coming in contact with 

 which it became shivered like melted glass poured into 

 water, and heated it so much as to cause the shores to be 

 strewed with dead fish for a distance of 20 miles. The 

 area covered by the lava was calculated at about 15 

 square miles, with an average depth of 12 feet, and the 

 lower pit of Kilauea, which was calculated to have held 

 15,400,000,000 cubic feet of molten matter, was emptied by 

 the discharge of the lava through the fissures by which it 

 was discharged at intervals. 



Ike ejection of cinders and ashes appears to be compara- 

 tively of rare occurrence ; they are, however, occasionally 

 thrown out. Thus, in 1789, a large volume of cinders and 

 sand is said to have been thrown to a great height, and 

 to have fallen in a destructive shower for many miles 

 around. Some men, belonging to an army then on its march, 

 are described by Dana to have been killed by this shower 

 of cinders, &c, while others perished from an emanation of 

 heated vapour or gas. 



The modern lava and volcanic glass of Kilauea are com- 

 posed of silica, protoxide of iron, alumina, soda, potash, and 

 lime, but these vary much in their relative proportions. 

 They contain a large amount of oxide of iron. Professor 

 Silliman, jun., asserts that soda is present to the exclusion 

 of potash, but this is not borne out bv Mr. Peabodv's ana- 



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